Conventional utility networks supply utilities for commercial, residential and industrial purposes. In a typical electrical distribution system, for example, electrical energy is generated by an electrical supplier or utility company and distributed to consumers via a power distribution network. The power distribution network is often a network of electrical distribution wires (more commonly known as “electrical transmission lines”) which link the electrical supplier to its consumers. Additional devices, such as bus bars, switches (e.g., breakers or disconnectors), power transformers, and instrument transformers, which are typically arranged in switch yards and/or bays, are automated for controlling, protecting, measuring, and monitoring of substations.
Typically, electricity from a utility is fed from a primary station over a distribution cable to several local substations. At the local substations, the supply is transformed by distribution transformers from a relatively high voltage on the distributor cable to a lower voltage at which it is supplied to the end consumer. From the local substations, the power is provided to industrial users over a distributed power network that supplies power to various loads. Such loads may include, for example, various power machines, lighting, HVAC systems, etc.
Electrical distribution panels (or “load centers”) are used widely in residential and commercial applications to house and protect electrical components. In centrally located electrical power distribution centers, for example, several electrical distribution panels are mounted together to house the main disconnect switches, multimeter centers, circuit breaker units, and bus bar ducting systems. These power distribution centers include a main bus bar arrangement that functions to connect the main electrical service entrance with a number of branch circuits. Other distribution panel assemblies are also known, including breaker panels which operate to divide electrical power into subsidiary circuits, while providing a protective fuse or circuit breaker for each circuit.
Indoor electrical enclosures, such as low-voltage, circuit protection load centers, often have a protective box with an open side for access to the interior of the enclosure. Prior art distribution panel enclosures typically comprise a container made of folded sheet metal or joined metal panels. The enclosure, in turn, is covered by a trim panel that is attached to the box with screws or bolts. The trim panel generally has a hinged access door which can be opened and closed for access to the circuit breaker actuation handles or other components located inside the distribution panel. The individual electrical components are mounted on a back-plate or back-panel that is secured to the interior of the enclosure case. The enclosure can be either surface mounted on a wall with the sides of the load center exposed, or flush mounted between studs or finished wall support members such that the finished wall surface, when installed, will be approximately flush with the outside edge of the load center enclosure.
Electrical enclosures are often required to accommodate a variety of component layouts, including acclimatizing to layouts with different sizes, numbers and arrangements of electrical conduits that pass through the enclosure. Some endwalls are provided with preformed “knock-out” openings through which the cables pass. However, knockout openings cannot be provided to accommodate every conceivable component layout. In other designs, holes must be cut in the endwall(s) to install conduits or other raceways intended to enter the enclosed panelboard. Aligning the cutouts in the endwall with the conduit, however, is often a very difficult and time-consuming task as the installer is typically required to take the entire enclosure off the wall, align and cut the holes, and remount the enclosure on the wall. There is therefore a need for an electrical enclosure design that allows for modification of the enclosure endwalls without dismounting the entire enclosure and without undermining the structural integrity and weather-resistant nature of the enclosure.